Hi, everyone! I useds Fluent to simulate the airflow in a small domain and the inlet boundary is velocity inlet (0.25m/s), ouflow as the outlet bondary. In the iteration, there are no reversed flow, but at the 12th iteration, reversed flow occured and solution is converged at the 97th step. I am not sure if the soulution can be reliable because of the reversed flow. The inlet is revised from a triangle (0.007m*0.007m*0.007m). I am not sure the reason of the reversed flow. Dose somebody expain my question? Thank you so so much!